In what feels like a blow to egalitarianism, new research finds that husbands and wives who assign housework along traditional gender lines have more sex than those who split the chores more equitably.

After reviewing data on how married couples in the U.S. tackle housework, as well as self-reports of how often they enjoyed intercourse, sociologists at the University of Washington (UW) say that couples who shared the burden of chores — cooking, cleaning and caring for the lawn — tend to have the least active sex lives.

The couples reported having sex about five times in the month before the survey began. But if the husband did no stereotypically female tasks (making meals, perhaps, or scrubbing floors), couples had sex 1.6 times more per month than couples in which husbands were responsible for doing all of those chores. Couples where the husband contributed to household chores, but stuck to the more stereotypically male tasks (car maintenance, bill paying, yard work) had sex .7 times more than those where the wife did all the male work.

That means that couples where husbands do no traditionally female tasks have sex the most: 4.85 times a month. Conversely, couples where men do all the female work have sex the least: 3.3 times a month.

The couples where husbands pitch in but do only the male tasks, fall somewhere in between; they’re sliding between the sheets 4.7 times a month. Meanwhile, couples where wives do all the male tasks have sex just under four times a month.

Overall, couples put in a combined 34 hours a week on traditionally female tasks compared to 17 hours on manly chores. Husbands performed about a fifth of classic women’s work and more than half of men’s work.

The findings, drawn from 4,500 heterosexual married U.S. couples participating in the National Survey of Families and Households, add some context to other studies that have found that husbands get more sex when they do more housework — a kind of domestic quid pro quo. But those conclusions didn’t quite ring true for Julie Brines, a co-author of the new study published in the American Sociological Review. She and her colleagues have done work suggesting that the division of housework doesn’t align with an “exchange model” where chores are traded for a share of income, for example, or sex.

Instead, Brines surmised that the relationship between sex and housework is actually far more complex. In actuality, it’s tied to stereotypical views of what qualifies as women’s — or men’s — work. And despite progress toward gender equality, “These are residues of sexual scripts that have been in place in our culture for a long time,” she says.

And what about the more important responsibility for couples with a family? This study did not take into account childcare as a household chore — most commonly performed by women but increasingly embraced by men — because the data used did not contain useful information about who cares for the kids. No one, notes Brines, has yet looked at whether dads who do more childcare get more sex.

It’s also worth pointing out that the national survey data was collected between 1992 and 1994, but Brines and her co-authors saythat the relationship between sex and housework has changed little since then. Research reveals only a modest evolution in the division of household labor over the past 18 years — mainly in the realm of childcare, with more dads stepping up.

Still, for the husbands who might be feeling smug about the results of her study, Brines has a bit of advice. “Don’t walk away from this research thinking, I should stay away from cooking or cleaning because I’ll benefit from it,” she cautions. “There may be costs associated with doing that.”

After all, a great sex life isn’t everything. Other research has found that neglecting to pitch in with dinner prep may create conflict in your marriage around the division of household labor. Men who shun cooking and cleaning can actually engender marital conflict which could also result in less sex. “There are trade-offs,” says Brines. And that’s putting it mildly.